Chip scale LED packaging method

ABSTRACT

A chip scale LED packaging method includes the following steps: clamping an upper mold with a plurality of through holes and a plate-shaped lower mold together; allowing bottoms of the plurality of through holes of the upper mold to be sealed by the plate-shaped lower mold to form a pattern of a plurality of grooves; placing chips one by one in corresponding through holes of the plurality of through holes; pouring encapsulation gel into each of the corresponding through holes; separating the upper mold from the plate-shaped lower mold after the encapsulation gel is cured and molded; and separating each cured and molded encapsulation gel from each of the corresponding through holes of the upper mold and taking each cured and molded encapsulation gel out of the upper mold to obtain an individual chip scale LED package.

(a) TECHNICAL FIELD OF THE INVENTION

The present invention relates to a light emitting diode (LED) packagingtechnology, and more particularly to a chip scale LED packaging method.

(b) DESCRIPTION OF THE PRIOR ART

As everyone knows, global warming is becoming more and more serious suchthat energy saving and carbon reduction has become a topic advocated byall countries in the world in recent years, allowing a variety ofenvironmentally friendly products conforming to energy-saving and carbonreduction to be taken seriously gradually. Among them, LED is a goodexample.

The so-called “chip class package” is the size of an encapsulation gelcovering around a chip being very close to the size of the chip; it isdefined generally as a packaging size being not more than 20% of thesize of a chip. A conventional chip scale packaging process, as shown inFIG. 1, mainly includes the following steps: laying a layer of fixingfilm for fixation of LED chips 30 onto a carrier board 60; distributinga number of LED chips 30 in an array pattern on the surface of thefixing film, a gap being kept between two adjacent LED chips 30 forsubsequent cutting; covering a layer of encapsulation gel on the arrayof LED chips 30; curing the encapsulation gel 40 by baking; cutting thearray of the LED chips 30 into individual chip scale LED packagingbodies 50; and taking the individual chip scale LED packaging bodies 50down from the fixing film.

However, the conventional chip scale packaging processes have thefollowing disadvantages:

-   -   1. the array arrangement of the chips 30, as FIG. 2 shows,        should not have any angular deviation upon the process; namely,        the high precision is required, resulting in reduced production        efficiency.    -   2. the position offset of the chip 30 must be smaller than 20        um; if the chip 30 is moved, a subsequent patch (surface mount        technology, SMT) cannot be used.    -   3. the array arrangement and cutting (indicated by cutting lines        L in FIGS. 3 and 4) must be aligned precisely; if the        positioning is not good, or the blade or the chip fixing        position is skew, it will cause a bad cutting, resulting in a        low cutting yield to form a high scrap rate.    -   4. the thickness of the encapsulation gel 40 is not easy to be        controlled even if it is the key to affect a color temperature        quality.    -   5. the cut individual chip scale LED packaging body 50 can only        be square or rectangular. However, individual single light        sources should have a variety of shape designs to meet market        use requirements so as to match secondary optics to conform to        lamp requirements.

SUMMARY OF THE INVENTION

The present invention proposes a chip scale LED packaging method,including the following steps: clamping an upper mold with a pluralityof through holes and a plate-shaped lower mold together; allowingbottoms of the plurality of through holes of the upper mold to be sealedby the plate-shaped lower mold to form a pattern of a plurality ofgrooves; placing chips one by one in corresponding through holes of theplurality of through holes; pouring encapsulation gel into each of thecorresponding through holes; separating the upper mold from theplate-shaped lower mold after the encapsulation gel is cured and molded;and separating each cured and molded encapsulation gel from each of thecorresponding through holes of the upper mold and taking each cured andmolded encapsulation gel out of the upper mold to obtain an individualchip scale LED package. The method can achieve accurate processing, thefacilities are simple and production efficiency is high without any lossresulting from cutting such that it is suitable for mass production tomeet the requirement of a large number of light sources in the market.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a conventional chip scale LED packingequipment and process;

FIGS. 2 to 4 are schematic views of arrangement and cutting conditionsof chips involved in the conventional chip scale LED packaging process;

FIG. 5 is a schematically perspective view of molds used according tothe present invention;

FIG. 6 is a schematically perspective view of the molds used accordingto the present invention while being combined together;

FIG. 7 is a top view of the molds used according to the presentinvention;

FIG. 8 is a cross-sectional view of the molds used according to thepresent invention;

FIG. 9 is a top view of the molds of the present invention after chipsare placed therein;

FIG. 10 is a cross-sectional view of the molds of the present inventionafter chips are placed therein;

FIG. 11 is a top view of the molds of the present invention afterencapsulation gel is poured in;

FIG. 12 is a cross-sectional view of the molds of the present inventionafter encapsulation gel is poured in;

FIG. 13 is a cross-sectional view of the molds of the present inventionwhile the lower mold is separated after the encapsulation gel is cured;

FIG. 14 is a schematic view of the molds of the present invention whilemolded encapsulation gel therein is being taken out;

FIG. 15 is a top view of a package individual of the present invention;

FIG. 16 is a cross-sectional view of the package individual of thepresent invention; and

FIG. 17 is a bottom view of the package individual of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 5 to 17, a chip scale LED packaging method accordingto the present invention includes the following steps: providing anupper mold 10 having a plurality of through holes 11 and a plate-shapedlower mold 20 as shown in FIG. 5; clamping the upper mold 10 and theplate-shaped lower mold 20 together as shown in FIG. 6; allowing theplate-shaped lower mold 20 to be connected to the upper mold 10 to sealthe bottoms of the plurality of through holes 11 of the upper mold 10 toform a plurality of bottom-sealed grooves as shown in FIGS. 7 and 8;placing chips 30 in a one by one manner in corresponding ones of theplurality of through holes 11 as shown in FIGS. 9 and 10; pouringencapsulation gel 40 into each of the corresponding through hole 11 asshown in FIGS. 11 and 12; separating the upper mold 10 from theplate-shaped lower mold 20 after the encapsulation gel 40 is cured andmolded as shown in FIG. 13; and finally, using a blanking die 70 toseparate each cured and molded encapsulation gel 40 from each of thecorresponding through holes 11 of the upper mold 10 and taking each ofthe cured and molded encapsulation get out of each of the correspondingthrough holes of the upper mold, thereby obtaining individual chip scalepackages 50 as shown in FIGS. 15, 16 and 17.

The present invention may use a upper mold 10 with through holes 11 of adifferent type to match the lower mold 20′ thereby making a variety oftypes of individual packages for optical design use.

The present invention has the following advantages:

-   -   1. using different upper and lower molds designs can make a        variety of shapes of chip scale LED package individuals for        optical design use compared with conventional manufacturing        methods, which can only make square or rectangular chip scale        LED package individuals.    -   2. the present invention can control the tolerances of the        package individuals more precisely compared to conventional        cutting manufacturing processes, and the thickness and exterior        dimension of the individual package is the key to control the        color temperature and light type of a light emitting individual.    -   3. each package individual of the present invention is made        independently, which will not cause the situation that the whole        batch production is scrapped due to some problems such as        arrangement or machine setting such that the productivity can be        increased relatively.    -   4. the manufacturing process of the present invention is        precise, the facilities simple and the productive efficiency        high without cutting tear and wear such that it is suitable for        mass production to meet the requirement of a large number of        light sources in the market.    -   5. conventional cutting processes must enlarge or widen the        distance of the encapsulation gel of chips, causing the material        waste, and the cutting cannot be carried out closely to the        chip, thereby avoiding damaging the chip such that the        encapsulation gel around the chip is thicker. But, the        manufacturing process of the present invention can make        ultra-small, ultra-thin package individuals, realizing a real        chip scale package (CSP).

I claim:
 1. A chip scale light emitting diode (LED) packaging method,comprising the following steps: clamping an upper mold having aplurality of through holes and a plate-shaped lower mold together;allowing bottoms of said plurality of through holes of said upper moldto be sealed by said plate-shaped lower mold to form a plurality ofbottom-sealed grooves that are separated from each other; placing a chipin each of said plurality of through holes; pouring encapsulation gelinto each of said plurality of through holes to enclose each of saidchips; separating said upper mold from said plate-shaped lower moldafter said encapsulation gel is cured and molded; and applying ablanking die from tops of said plurality of through holes of said uppermold to simultaneously drive said chips out of said plurality of throughholes of said upper mold for separating each said cured and moldedencapsulation gel from each of said plurality of through holes of saidupper mold and taking each said cured and molded encapsulation gel outof said upper mold to obtain an individual chip scale LED package.